X-numărul
(X+X:2+X:4)×2,5=31,5
(X/1+X/2+X/4)×25/10 simplificat cu 5=315/10 simplificat cu 5
4×X+2×X+X totul supra/4 ×5/2=63/2
7X/4=63/2:5/2
7X/4=63/2×2/5
7X/4=63×1 totul supra/5
7X/4=63/5
7X=63/5 ×4/1
7X=63×4 totul supra/5
7X=252/5
X=252/5 :7/1
X=252/5×1/7
X=36×1 totul supra/5×1
X=36/5
X=36:5=7,2